This invention relates to shock absorbing pads for a missile and more particularly to shock absorbing pads disposed in a missile launch tube.
One of the basic missile launcher design concepts consists of launching the missile "bare", that is, preventing the missile from contact with the submarine structure and launcher hard areas, and guiding the missile out of the launch tube with the use of structured elastomeric pads bonded to the wall of the launch tube. While the launching function of the elastomeric pad may be their primary function, they must satisfactorily perform at least two other critical functions; guiding the missile into the launch tube during a loading operation, and protecting the missile from shock and vibration while the missile is stored within the launch tube. In each of the above functions, the issue of rattle space or space available for movement of the missile within the launch tube is central to the intended function of the elastomeric pads. During the loading operation, if a greater amount of space is available for the missile, less exact positioning loading equipment may be utilized. Also, when resisting shock, greater available space gives greater protection for a given maximum acceleration of the missile. During launching a greater amount of available space allows for higher cross flows resulting either from motion of the submarine or from movement of the sea.
Any elastomeric pad concept which reduces the net available space for lateral missile motion is undesirable. However, some applications of elastomeric pad technology require a rather high individual pad compression-deflection characteristic, which for the most part, comes at the expense of reduced space available for lateral motion.
In the prior art as shown in FIG. 1, a missile is installed in a launch tube and is prevented from contacting the tube by the elastomeric pads disposed in the annular space between the missile and the launch tube. The missile is shown in its equilibrium or neutral position at rest in the central portion of the launch tube. In this position, there is no force exerted by the elastomeric pads. As the missile is moved in any direction from the central position, it compresses the elastomeric pads, exerting a force on the missile intended to return it to the central position. Essentially, the only force exerted to restore the missile to its central position within the launch tube is the compressive reactant forces within the pads themselves. The pads are normally lined with teflon so that the pads on the side of the missile exert a very low coefficient of friction between the pad and the missile so that the shear forces which would retard movement of the missile are considered negligible. The pads diametrically opposed from those compressed exert no force on the missile so that the only force exerted on the missile to restore it to its central position are from the compressing forces exerted on the pads that are compressed as the missile contacts the elastomeric pads.